1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device with lower power consumption.
2. Discussion of Related Art
A liquid crystal display displays images by controlling the light transmittance of a liquid crystal with dielectric anisotropy. The liquid crystal display device includes a liquid crystal panel where liquid crystal cells are arranged in a matrix and a driving circuit for driving the liquid crystal panel.
The liquid crystal panel displays predetermined images corresponding to the light transmittance of each liquid crystal cell. A liquid crystal panel can be categorized into a vertical electric field application type or a horizontal electric field application type according to a direction of electric field for driving a liquid crystal.
The vertical electric field application type liquid crystal panel drives a twisted nematic (TN) liquid crystal by vertical electric field formed between a common electrode and a pixel electrode disposed to oppose each other on an upper substrate and a lower substrate. The vertical electric field application type liquid crystal panel has an advantage of a good aperture ratio but a disadvantage of a narrow viewing angle.
The horizontal electric field application type liquid crystal panel drives an in-plane switch (IPS) liquid crystal by utilizing horizontal electric field between a pixel electrode and a common electrode disposed to be parallel with each other on a lower substrate. Such a horizontal electric field application type liquid crystal panel has an advantage of a wide viewing angle but a disadvantage of low aperture ratio and transmittance.
Recently, in order to solve the disadvantage of the horizontal electric field application type liquid crystal panel, a fringe field switching (hereinafter, referred to as “FFS”) type liquid crystal panel has been proposed, which operates by utilizing a fringe field. The FFS type liquid crystal panel includes a common electrode and a pixel electrode having an insulating layer therebetween. Such a FFS type liquid crystal panel drives a liquid crystal between the upper and lower substrates by utilizing the fringe field between the common electrode and the pixel electrode, thereby improving aperture ratio and transmittance.
The common electrode of such a FFS type liquid crystal display device is formed to cover an effective display region of the liquid crystal panel on the insulating layer. However, if the common electrode is formed to cover the effective display region of the liquid crystal panel, there is high capacitance in an overlapped region with a data line. The high capacitance in the overlapped region with the data line causes the liquid crystal panel to have higher power consumption.